DKK4 and renal cell carcinoma: From a previous proteomics study, matrix metalloproteinase 9, ceruloplasmin, podocalyxin, Dickkopf-related protein 4, and carbonic anhydrase IX were increased, whereas AQP-1, extracellular matrix metalloproteinase inducer, neprilysin, dipeptidase-1, and syntenin-1 were decreased in urinary exosomes derived from RCC patients (Raimondo et al., 2013).